The present invention relates to a wiper blade with a wind scoop elastically supported on the wiper blade in front of it, the wiper blade being adapted to rest with its wiper lip on a windshield of a motor vehicle and the wind scoop comprising an elastic lip arranged in close proximity to the windshield so as to contact the windshield during a downward motion of the wiper blade on the windshield.
Known windshield wipers have a wiper arm, which is comprised of a fastening part attached to a drive axle, a pivoting part connected to it an elbow joint, and a wiper rod that is rigidly connected to the pivoting part. Furthermore, the windshield wiper has a wiper blade which has a support bracket system and a rubber wiper element supported by this bracket system. The wiper blade is coupled to the wiper arm by virtue of the fact that a hook-shaped end of the wiper rod engages between two side walls of the support bracket system and encloses a hinge bolt. The joint thus formed guides the wiper blade with the rubber wiper element over a motor vehicle window, wherein the pivoting part and the support bracket system make it possible for the rubber wiper element to adapt to a curvature of the motor vehicle window. A required pressure of the rubber wiper element against the vehicle window is produced with at least one tension spring, which secures the fastening part and the pivoting part together with the wiper rod by way of the elbow joint.
The rubber wiper element is comprised of an elastomer. It has a top strip which is connected by way of an intermediary tilting piece to a wiper lip that rests against the window to be wiped. By means of the intermediary tilting piece, the wiper lip can turn over into the opposite direction at the reversal point of the wiping motion so that it always assumes a favorable angle to the windshield. When the windshield wiper is actuated, the rubber wiper element slides together with the wiper lip over the vehicle window. When the vehicle is being driven, a driving wind flows underneath the wiper arm and the wiper blade and generates a force counter to the pressing force of the tension spring. Particularly at high speeds, the pressing force of the wiper blade against the windshield can be reduced by the driving wind to the point that the wiper blade lifts up from the windshield or floats on a water film, or that the wiper lip of the rubber wiper element is blown around. This leads to the fact that the wiper blade rattles against the windshield and the cleaning quality is insufficient.
It is known to fasten a wind scoop on the driver""s side, in front of the wiper blade in the downward wiping direction, which conveys the driving wind over the wiper blade and thereby presses the wiper blade against the vehicle window. In order to prevent the driving wind from flowing underneath the wind scoop and thereby producing wind noise and reducing the pressing force, the wind scoop should be disposed with a lower edge as close as possible to the windshield. The inclination of the wiper blade and therefore the distance of the wind scoop from the windshield, however, is a function of many influence quantities which change over time and have reciprocal relationships to one another.
The wiper arm and wiper blade are comprised of a number of individual components, a number of which are connected to one another by way of hinged joints. With increasing hours of operation of the wiper blade and wiper arm, the play between the components increases and the torsional and flectional resistance moments of the individual components decreases.
In addition, friction forces and normal forces act on the wiper arm and wiper blade, and driving forces and wind forces act between the wiper lip and the windshield. Depending on the wiping direction, the friction force is directed counter to this wiping direction and depends on the state of the rubber wiper element, the weather conditions, the wiping speed, and the direction and intensity of the wind forces, which are produced by the driving wind and by cross-winds and have an effect on the normal force and friction force between the windshield and the wiper blade. Furthermore, the curvature of the windshield and thereby the inclination in relation to the wiper blade differs depending on the position of the wiper blade.
The smaller the distance of the wind scoop from the windshield, the better the driving wind is conveyed over the wiper blade, but this also means that with different influence quantities that have an impact on one another, the wind scoop comes into contact with the windshield more easily.
DE 195 28 015 C1 has disclosed a wind scoop to which an elastic wind deflection element is fastened which is disposed approximately parallel to the wiper lip close to the windshield and is elastically supported or can be deformed so that influenced by the driving wind at higher driving speeds of the vehicle, this wind deflection element contacts the windshield in at least one wiping region. If the elastic wind deflection element comes into contact with the windshield, an impact noise is thereby produced, the pressing force of the wiper lip against the windshield is abruptly reduced, which can lead to the fact that the wiper blade begins to rattle and the wiper lip floats on the surface. Furthermore, with certain influence quantities such as drizzle, the wind deflection element can be induced to execute vibrations that are transmitted to the wiper blade and cause it to rattle.
It is an object of the present invention to provide an improved wiper blade and wind scoop of the above-described type for cleaning a windshield of a motor vehicle, which does not have the above-described disadvantages.
According to the invention, a wind scoop is fastened to a wiper blade or wiper arm and is disposed in front of the wiper blade in the downward wiping direction. The wind scoop has an elastically soft lip that points toward the windshield and is inclined toward the wiper lip. The wind scoop is disposed with the elastically soft lip particularly close above the windshield, but far enough away that normally and in particular with the upward wiping motion, the lip is always guided closely above the windshield. With a downward wiping motion in the direction of the wind scoop, the wiper blade and the wiper arm with the wind scoop are rotated toward the windshield, by means of which the distance decreases between the wind scoop or the lip and the windshield. If different influence quantities also occur during the downward wiping motion, e.g. a strong driving wind, high friction forces, a rapid wiping speed, etc., so that the wind scoop meets the windshield with the elastically soft lip, the lip is deflected in the direction of the wiper lip and elastically compensates for or cushions the movement energy of the wind scoop and the wiper blade by means of a rolling motion. The further the lip is deflected in the direction of the wiper lip via the spring deflection by means of the movement energy of the wind scoop and the wiper blade, the smaller the lever arm becomes via which the movement energy deflects the lip, and the more material is elastically deformed, which produces a favorable transition from a small reaction force to a greater reaction force via a spring deflection that is on the whole large. A favorable transition can also be encouraged through the selection of the contour of the lip, for example by virtue of the fact that it tapers in the direction of the windshield. The small reaction force at the beginning of the spring deflection and the rolling motion prevent an audible impact noise of the wind scoop or lip against the windshield and reduce the pressing force of the wiper lip only slightly and in particular, not abruptly. The wiper blade does not begin to rattle and does not float on the surface. Due to the angled contour, the elastically soft lip has a greater flectional resistance moment in relation to the wind force, by means of which it is less easily blown around and flowed under by the driving wind. As a result of the angled contour, not only do bending moments act on the lip starting from the beginning of the spring deflection, but so do tensile forces counter to the wiping motion, which prevent a vibration of the lip, which could lead to a rattling of the wiper blade.
In windshield wiper systems with two wiper arms, the wind scoop can be attached to each wiper blade or wiper arm or can also be attached in windshield wiper systems with one wiper arm. The most important wiping region is on the driver""s side and thus at least one wind scoop is disposed in front of the wiper blade in the downward wiping direction on the driver""s side.
According to one embodiment of the invention, the lip is stepped, waved, or zigzagged in the region with which it comes into contact with the windshield. The wind scoop thus contacts the windshield with a smaller area. At the beginning of the spring deflection, less material is deformed by means of the movement energy, the reaction force is reduced, and the impact noise is further reduced. Moreover, the friction force and in particular the adhesion are reduced.
This can be achieved with a lip that is stepped, zigzagged, or waved on the end face, or also with a lip whose material thickness varies in a stepped, zigzagged, or waved fashion in the direction of the wiper lip. Suitably, the zigzags, waves, and/or steps of the lip are embodied with a height of less than 2 mm. At a distance of approx. 0 to 2 mm above the windshield, a flow velocity by means of the driving wind can be rendered virtually negligible. Despite a small contact area, the wind is prevented from flowing under the lip.
In one embodiment of the invention, the wind scoop is elastically connected to the wiper blade or the wiper arm.
The distance of the wind scoop or lip from the windshield is thus adjusted independently of the driving wind. At higher driving speeds and therefore with a stronger driving wind, the wind scoop is pressed closer to the windshield and the wiper blade is prevented from lifting up. At lower driving speeds, the wind scoop can be farther away from the windshield without the wind scoop being lifted. Moreover, the wind scoop is secured against coming into contact with the windshield in an undesirable fashion at low driving speeds. A stop of the elastic support in the direction of the windshield can be selected so that at the maximum speed, the wind scoop comes to rest with the lip close above the windshield and only with the occurrence of additional influence quantities, does the lip of the wind scoop come into contact with the windshield during the downward wiping motion, e.g. with the occurrence of increased friction. However, it is also possible that starting from a certain speed, the lip comes into contact with the windshield during the downward wiping motion.
The lip can be attached to the wind scoop as an additional component. Preferably, however, the wind scoop is a dual component part, with a rigid component and with the elastically soft lip. The number of individual parts is reduced, an assembly step is saved, and the danger of the fastening becoming detached is prevented.
In order to produce the dual component wind scoop, a process is proposed in which at the beginning, the rigid component is cast in a first casting mold. After the material has hardened, material for the lip is injected into a recess in the rigid component and in a second casting mold disposed on the rigid component. After the material has assumed an elastically soft state, the second casting mold is removed. The lip is thus forcibly removed from the mold by virtue of the fact that it is temporarily deflected into a straight form. A reasonably priced one-piece casting mold can be used for the lip. The manufacturing process is comprised of a few separate process steps and is simple and fast. Furthermore, the lip is securely connected to the rigid component. However, the lip can also be separately cast and then threaded into the rigid component.